Prosthetic heart valve

ABSTRACT

Disclosed prosthetic valves can comprise a sewing ring configured to secure the valve to an implantation site. Some disclosed valves comprise a resiliently collapsible frame having a neutral configuration and a collapsed deployment configuration. Some disclosed frames can self-expand to the neutral configuration when released from the collapsed deployment configuration. Collapsing a disclosed valve can provide convenient access to the sewing ring, such as for securing the valve to the implantation site, as well as for the insertion of the valve through relatively small surgical incisions.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication No. 61/332,885, filed May 10, 2010, which is incorporatedherein by reference. This application also claims the benefit of U.S.Provisional Patent Application No. 61/472,083, filed Apr. 5, 2011, whichis incorporated herein by reference.

FIELD

The present application concerns implantable prosthetic valves andrelated methods and systems, such as for example, prosthetic aorticvalves that can be implanted using minimally invasive surgicaltechniques.

BACKGROUND

In vertebrate animals, the heart is a hollow muscular organ having fourpumping chambers as seen in FIG. 1: the left and right atria and theleft and right ventricles, each provided with its own one-way valve. Thenatural heart valves are identified as the aortic, mitral (or bicuspid),tricuspid and pulmonary, and are each mounted in an annulus comprisingdense fibrous rings attached either directly or indirectly to the atrialand ventricular muscle fibers. Each annulus defines a flow orifice.

The atria are the blood-receiving chambers, which pump blood into theventricles. The ventricles are the blood-discharging chambers. A wallcomposed of fibrous and muscular parts, called the interatrial septumseparates the right and left atriums (see FIGS. 2, 3 and 4). The fibrousinteratrial septum is a materially stronger tissue structure compared tothe more friable muscle tissue of the heart. An anatomic landmark on theinteratrial septum is an oval, thumbprint sized depression called theoval fossa, or fossa ovalis (shown in FIG. 4).

The synchronous pumping actions of the left and right sides of the heartconstitute the cardiac cycle. The cycle begins with a period ofventricular relaxation, called ventricular diastole. The cycle ends witha period of ventricular contraction, called ventricular systole. Thefour valves (see FIGS. 2 and 3) ensure that blood does not flow in thewrong direction during the cardiac cycle; that is, to ensure that theblood does not back flow from the ventricles into the correspondingatria, or back flow from the arteries into the corresponding ventricles.The mitral valve is between the left atrium and the left ventricle, thetricuspid valve between the right atrium and the right ventricle, thepulmonary valve is at the opening of the pulmonary artery, and theaortic valve is at the opening of the aorta.

FIGS. 2 and 3 show the anterior (A) portion of the mitral valve annulusabutting the non-coronary leaflet of the aortic valve. The mitral valveannulus is in the vicinity of the circumflex branch of the left coronaryartery, and the posterior (P) side is near the coronary sinus and itstributaries.

The mitral and tricuspid valves are defined by fibrous rings ofcollagen, each called an annulus, which forms a part of the fibrousskeleton of the heart. The annulus provides peripheral attachments forthe two cusps or leaflets of the mitral valve (called the anterior andposterior cusps) and the three cusps or leaflets of the tricuspid valve.The free edges of the leaflets connect to chordae tendineae from morethan one papillary muscle, as seen in FIG. 1. In a healthy heart, thesemuscles and their tendinous chords support the mitral and tricuspidvalves, allowing the leaflets to resist the high pressure developedduring contractions (pumping) of the left and right ventricles.

When the left ventricle contracts after filling with blood from the leftatrium, the walls of the ventricle move inward and release some of thetension from the papillary muscle and chords. The blood pushed upagainst the under-surface of the mitral leaflets causes them to risetoward the annulus plane of the mitral valve. As they progress towardthe annulus, the leading edges of the anterior and posterior leafletcoapt and form a seal, closing the valve. In the healthy heart, leafletcoaptation occurs near the plane of the mitral annulus. The bloodcontinues to be pressurized in the left ventricle until it is ejectedinto the aorta. Contraction of the papillary muscles is simultaneouswith the contraction of the ventricle and serves to keep healthy valveleaflets tightly shut at peak contraction pressures exerted by theventricle. The remaining cardiac valves operate in a similar fashion.

Various surgical techniques may be used to repair a diseased or damagedvalve. In a valve replacement operation, the damaged leaflets aretypically excised and the annulus sculpted to receive a prostheticvalve. Due to aortic stenosis and other heart valve diseases, thousandsof patients undergo surgery each year wherein the defective native heartvalve is replaced by a prosthetic valve (either bioprosthetic ormechanical). Another, less drastic, method for treating defective valvesis through repair or reconstruction, which is typically used onminimally calcified valves. One problem with surgical therapy is thesignificant insult it imposes on chronically ill patients and theassociated high morbidity and mortality rates associated with surgicalrepair.

When a valve is replaced, surgical implantation of the prosthetic valvehas typically required an open-chest surgery, during which the heart isstopped and the patient is placed on cardiopulmonary bypass (a so-called“heart-lung machine”). In one common surgical procedure, the diseasednative valve leaflets are excised and a prosthetic valve is sutured tothe surrounding tissue of the valve annulus. Because of the traumaassociated with the procedure and the attendant duration ofextracorporeal blood circulation, mortality rates during surgery orshortly thereafter typically have been high. It is well established thatrisks to patients increase with the duration of extracorporealcirculation. Due to such risks, a substantial number of patients withdefective valves are deemed inoperable because their condition is toofrail to withstand the procedure. By some estimates, up to about 50% ofpatients suffering from aortic stenosis and who are older than 80 yearscannot undergo surgery for aortic valve replacement using conventionalopen-chest surgery.

Because of drawbacks associated with conventional open-heart surgery,percutaneous and minimally-invasive surgical approaches are garneringintense attention. Minimally invasive surgical techniques have been andcontinue to be developed. In successfully performed minimally invasivetechniques, a conventional sternotomy can be avoided. Access to theheart can be by way of upper sternotomy or thoracotomy allowing asmaller incision and typically shorter healing times, as well as lesspain for the patient. Blood loss is typically lower with minimallyinvasive techniques, hospital stays are shorter, and there may be lowermorbidity and mortality rates as compared to conventional surgicaltechniques.

To obtain at least some of the potential benefits of the smallerincisions required by minimally invasive surgical techniques, prostheticvalves compatible with such techniques are needed. For instance, U.S.Pat. No. 5,411,522 to Andersen et al. describes a collapsible valvepercutaneously introduced in a compressed state through a catheter andexpanded in the desired position by balloon inflation.

Although such remote implantation techniques have shown great promisefor treating certain patients, replacing a valve via surgicalintervention is still the preferred treatment procedure. One hurdle tothe acceptance of remote implantation is resistance from doctors who areunderstandably anxious about converting from an effective, if imperfect,regimen to a novel approach that promises great outcomes but isrelatively foreign. In conjunction with the understandable cautionexercised by surgeons in switching to new techniques of heart valvereplacement, regulatory bodies around the world are moving slowly aswell. Numerous successful clinical trials and follow-up studies are inprocess, but much more experience with these new technologies will berequired before they are widely accepted. Additionally, the long-termdurability of remotely implanted devices is unknown.

In another approach, a flexible heart valve especially suitable forimplanting in the aortic annulus has been proposed in U.S. Pat. No.6,558,418 to Carpentier, et al., and U.S. Pat. No. 6,376,845 to Marquez,et al. More particularly, Carpentier and Marquez disclose single andmulti-element frame-and-stent assemblies that include flexible cuspsbetween adjacent commissure portions extending therefrom. Asuture-permeable connecting band attached to the disclosed prostheticvalve follows the shape of (i.e., is coextensive with) the underlyingframe. In the Carpentier and Marquez approach, the valve is secured byattaching the connecting band (and thereby, the entire contour of theunderlying frame, including the cusp and commissure portions) to thesurrounding natural tissue. Although this approach represents anadvancement of surgically implantable valves, the commissure portions ofthe frame remain fixedly attached to, and cannot move independently of,the tissue since the sewing band is coextensive with the undulatingframe. In addition, suturing the complex, undulating periphery of thesewing band can be difficult and time consuming, as various parts of thevalve can interfere with access to the sewing band. Although the valvesdisclosed in the '418 and '845 patents could be collapsed and insertedthrough a small incision, such as a thoracotomy, it would be difficultto suture them to the native annulus through such a small incision dueto the configuration of the sewing band.

Accordingly, there remains a need for an improved prosthetic heart valvethat facilitates placement through small incisions, facilitates easiersuture tying at the implantation site, and provides improvedhemodynamics. In addition, devices for, and associated methods of,implanting such improved prosthetic valves in a body lumen are alsoneeded, especially a more efficient procedure that reduces the durationa patient needs extracorporeal circulation to undergo a cardiac valvereplacement.

SUMMARY

The present disclosure concerns embodiments of a prosthetic valve,delivery devices for the valve and methods for implanting the valve. Thevalve can be implanted at any of the native valve annuluses of the heartor within any other body lumen that requires a valve to regulate theflow of liquid (e.g., a vein). The valve in particular embodiments has aresiliently flexible, self-expandable frame that supports afluid-occluding member, such as a leaflet structure comprising aplurality of leaflets. The valve frame desirably has flexible commissureposts that support the commissures of the leaflets. The valve frame canbe placed in a collapsed delivery configuration to facilitate insertionof the valve into the body and attachment (e.g., by suturing) of thevalve to a native annulus, such as the native aortic annulus. Forexample, the valve frame can allow the valve to be radially collapsed sothat the valve can be more easily inserted through a surgical incisionmade in a body lumen in a minimally invasive surgical procedure.

The valve frame desirably is also configured to be longitudinallycollapsible by folding the commissure posts inwardly toward a sewingring of the valve. During implantation of the valve, the commissureposts can be retained in the longitudinally collapsed state to providethe surgeon greater access to the sewing ring for suturing (or otherwisesecuring) the sewing ring to the native annulus. After the valve issecured to the native annulus, the commissure posts can be released fromthe collapsed state so as to allow the commissure posts to self-expandto a deployed, functional state.

The commissure posts, in the deployed state, extend longitudinally fromthe sewing ring and can extend radially outward relative to alongitudinal axis of the valve. The outward lean of the commissure postsallow the leaflets to open to a relatively larger outlet opening duringsystole, thereby reducing the pressure gradient across the valvecompared to commissure posts that are parallel to the longitudinal axisof the valve. In addition, the commissure posts can flex slightlyinwardly and outwardly relative to the longitudinal axis of the valveduring the cardiac cycle, which allows the leaflets supported by thecommissure posts to close more gently and relieves stress on theleaflets during diastole.

In one representative embodiment, a prosthetic valve comprises an inflowend and an opposing outflow end defining a valve axis extendinglongitudinally of the ends, and a plurality of valve leaflets. The valvealso comprises a collapsible, self-expandable frame assembly configuredto support the valve leaflets and defining a plurality of commissureportions, and a sewing ring portion configured to secure the valve to asurrounding lumen, wherein the plurality of commissure portions areconfigured to move independently of the sewing ring when the valve is sosecured.

In another representative embodiment, a prosthetic-valve delivery systemcomprises a prosthetic valve and a delivery device. The prosthetic valveis collapsible and expandable between a collapsed delivery configurationand a neutral configuration. The valve also comprises a sewing ringconfigured to be secured to an implantation site, and a resilient frameconfigured to cause the valve to expand from the collapsed deliveryconfiguration to the neutral configuration. The delivery device isconfigured to assist the delivery of the valve to the implantation sitewhen the valve is in the collapsed delivery configuration.

In another representative embodiment, a method of implanting aprosthetic valve at an implantation site within a body lumen isprovided. The valve comprises a resilient frame and a sewing ring, andis configured to at least partially self-expand to a neutralconfiguration from a collapsed delivery configuration. The methodcomprises retaining a valve in a collapsed delivery position, making anincision in a body lumen adjacent an implantation site, inserting thecollapsed valve through the incision, securing the sewing ring tosurrounding tissue within the body lumen, and releasing the valve fromthe collapsed delivery configuration such that the valve independentlyrecovers to the neutral configuration within the body lumen.

The foregoing and other objects, features, and advantages of theinvention will become more apparent from the following detaileddescription, which proceeds with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an anatomic anterior view of a human heart, withportions broken away and in section to view the interior heart chambersand adjacent structures.

FIG. 2 illustrates an anatomic superior view of a section of the humanheart showing the tricuspid valve in the right atrium, the mitral valvein the left atrium, and the aortic valve in between, with the tricuspidand mitral valves open and the aortic and pulmonary valves closed duringventricular diastole (ventricular filling) of the cardiac cycle.

FIG. 3 shows an anatomic superior view of a section of the human heartshown in FIG. 2, with the tricuspid and mitral valves closed and theaortic and pulmonary valves open during ventricular systole (ventricularemptying) of the cardiac cycle.

FIG. 4 shows an anatomic anterior perspective view of the left and rightatria, with portions broken away and in section to show the interior ofthe heart chambers and associated structures, such as the fossa ovalis,coronary sinus and the great cardiac vein.

FIG. 5A illustrates an isometric view of one embodiment of a prostheticvalve of the type disclosed herein (e.g., a prosthetic aortic valve).

FIG. 5B shows a partially exploded view of the prosthetic valve assemblyshown in FIG. 5A.

FIGS. 6A and 6B are schematic longitudinal cross-sectional views of thevalve shown in FIGS. 5A and 5B installed in, for example, an aorticannulus. FIG. 6A shows systole and FIG. 6B shows diastole.

FIG. 7 shows a cross-sectional view taken along section line 7-7 shownin FIG. 5.

FIG. 8 illustrates a collapsible, self-expandable wireform frame of thetype incorporated in the valve shown in FIG. 5. FIG. 8A is a side viewshowing a commissure post angled outwards relative to a longitudinalaxis.

FIG. 9 shows the wireform frame shown in FIG. 8 in an axially (orlongitudinally) collapsed position.

FIG. 10 shows FIG. 8 superimposed on FIG. 9, illustrating the extent towhich the disclosed frame can elastically collapse in an axial (orlongitudinal) direction relative to the uncollapsed position.

FIG. 11 shows the wireform frame in FIG. 8 in a radially collapsedposition.

FIG. 12 shows a top plan view of the frame shown in FIG. 8.

FIG. 13 shows FIG. 11 superimposed on FIG. 12, illustrating the extentto which the disclosed frame can elastically collapse in a radialdirection relative to the uncollapsed position.

FIGS. 14-27 show several intermediate constructs arising from severaltechniques for manufacturing a frame of the type shown in FIG. 8.

FIG. 14 shows a sheet of material from which a disclosed frame can beformed, such as by laser-cutting.

FIG. 15 shows a laser-cut flat pattern formed from the sheet shown inFIG. 14.

FIG. 16 shows a hollow cylinder (a tube) from which a disclosed framecan be laser-cut.

FIG. 17 shows a laser-cut cylindrical pattern formed from the hollowcylinder shown in FIG. 16.

FIG. 18 shows a laser-cut pattern (e.g., as shown in FIG. 15 or FIG. 17)in a first shape-setting position on a first mandrel.

FIG. 19 shows the laser-cut pattern shown in FIG. 18 in a secondshape-setting position on a second mandrel.

FIG. 20 shows an isometric view of a finished frame of the type shown inFIG. 8.

FIG. 21 shows a wire from which a disclosed frame can be formed.

FIG. 22 shows the wire shown in FIG. 21 on a first wireforming mandrel.

FIG. 23 shows the wire after forming and shape setting and removal fromthe mandrel shown in FIG. 22.

FIG. 24 shows the formed wire shown in FIG. 23 on a second wireformingmandrel, similar to the mandrels shown in FIGS. 18 and 19.

FIG. 25 shows the wire after undergoing a shape setting process andremoval from the mandrel shown in FIG. 24.

FIG. 26 shows a crimp sleeve for joining opposing ends of the formedwire.

FIG. 27 shows a completed wireform frame of the type shown in FIG. 8.

FIG. 28 shows a plan view of a leaflet as disclosed herein positionedbeneath a conventional leaflet. As shown in FIG. 28 and discussed morefully below, the disclosed leaflet has a varying radius of curvature anda corresponding broader body relative to the conventional leaflet.

FIG. 29 shows a leaflet as disclosed herein.

FIG. 30 shows an isometric view of the frame shown in FIG. 8 partiallycovered by a cloth frame cover.

FIG. 31 shows an isometric view of the frame shown in FIGS. 8 and 23covered by the cloth frame cover shown in FIG. 30.

FIG. 32 shows an exploded view of an assembly comprising the coveredframe shown in FIG. 31 and three leaflets of the type shown in FIG. 29.

FIG. 33 shows an isometric view of the assembly shown in FIG. 32.

FIG. 34 shows a top plan view from above the assembly shown in FIGS. 25and 26.

FIG. 35 shows a top plan view from below the assembly shown in FIGS. 25and 26.

FIG. 36 shows an isometric view of a collapsible stent as disclosedherein.

FIG. 37 shows an isometric view of the collapsible stent shown in FIG.36 in an axially (or longitudinally) collapsed position.

FIG. 38 shows a side elevation view of the axially collapsed stent shownin FIG. 37.

FIG. 39 shows an isometric view of a sewing ring insert as disclosedherein.

FIG. 40 shows a side elevation view of the sewing ring insert shown inFIG. 39.

FIG. 41 shows an exploded view of a partial assembly comprising thestent shown in FIG. 36, the sewing ring insert shown in FIG. 39 and atubular covering cloth for joining the stent and the sewing ring insertas shown, for example, in FIG. 7.

FIGS. 42A-42C show various views of a prosthetic valve mounted on avalve holder that can be used to deliver a valve to an implantationsite. The illustrated holder retains the commissure portions of thevalve in at least a partially collapsed configuration, which allows forincreased access to the sewing ring portion of the valve for attachmentto the native annulus during implantation. FIG. 42C shows the valve in apartially “ovaled” configuration for easier insertion through a narrowsurgical opening, such as a thoracotomy.

FIG. 42D shows a delivery device comprising the valve holder, shaft andhandle attached to the shaft opposite the valve holder.

FIG. 43 shows a valve as disclosed herein in a collapsed deliveryconfiguration and being delivered to, for example, the aortic annulususing a “parachuting” delivery technique.

FIG. 44 is a graph illustrating the pressure gradient measured acrossvalves having a conventional leaflet and frame design and valves havinga modified leaflet and frame design according to the present disclosure.

FIG. 45 shows a perspective view of another embodiment of a leafletsupport stent for use with the disclosed prosthetic heart valve frame.

FIG. 46 shows a side elevation view of the leaflet support stent shownin FIG. 45, combined with a sealing ring and having a cloth coveringsurrounding it.

FIG. 47 shows a top plan view of the cloth-covered leaflet support stentof FIG. 46, in a radially compressed configuration.

DETAILED DESCRIPTION

The following describes principles related to implantable prostheticvalves and related methods and systems with reference to exemplaryprosthetic valves, delivery systems, and manufacturing and assemblymethods. One or more of the disclosed principles can be embodied in manydifferent configurations to accommodate various design objectives. Somedisclosed valves and delivery systems can be used in conjunction withminimally invasive surgical techniques. However, prosthetic cardiacvalves and delivery systems compatible with minimally-invasive surgical(MIS) techniques are but examples of the wide variety of prostheticvalves and related methods and systems incorporating the principlesdisclosed herein.

Overview

As described more fully below and shown in the accompanying drawings(e.g., FIGS. 5A and 5B), valves as disclosed herein can comprise aresiliently collapsible frame in combination with a valve securingportion (e.g., an annular sewing ring) for securing the valve to thetissue of a surrounding body lumen. Such frames allow disclosed valvesto be retained in a collapsed deployment configuration so as to provide,among many advantages, convenient access to the securing portion, whilemaintaining the ability to self-expand upon being released from thedeployment configuration.

As used herein, “self expand” means to elastically recover from acollapsed (e.g., a compressed) configuration when an external restraint(e.g., a suture, a sheath or a holder) is removed.

As used herein, a “neutral position” or a “neutral configuration” meansa configuration of a valve and/or a frame when the respective valveand/or frame is at-rest (e.g., still) and free from externally appliedloads (e.g., pressure gradients through the valve, forces applied byretaining and/or delivery devices to retain the valve in a collapsedconfiguration).

As used herein, a “deployed neutral configuration” means a configurationof a valve and/or a frame when the respective valve and/or frame is inan expanded state within a body lumen during implantation and is freefrom externally applied loads (e.g., pressure gradients through thevalve) other than those external forces resulting, at least in part,from contact with a surrounding tissue.

As used herein, an “implanted neutral position” or an “implanted neutralconfiguration” means a configuration of a valve and/or a frame when thevalve is implanted in a body lumen and secured to surrounding tissue,and is free from externally applied loads (e.g., pressure gradientsthrough the valve) other than those external forces resulting, at leastin part, from attachment to the tissue. Stated differently, an“implanted neutral configuration” means the expanded configuration ofthe valve immediately following implantation.

In many instances, a valve's neutral configuration and implanted neutralconfiguration are substantially the same configuration, but this neednot be the case (e.g., a valve can be slightly over-sized relative tothe surrounding tissue of a body lumen, such that forces applied by thesurrounding tissue slightly deforms the valve in its implanted neutralconfiguration, relative to the neutral position). As discussed below andshown in FIGS. 6A and 6B, the valve configuration changes from theimplanted neutral configuration during diastole and systole.

Some resilient support structures (or frames) allow the supportstructure to resiliently expand between a substantially collapsedconfiguration (e.g., a delivery configuration as shown in FIGS. 9 and11) and a substantially undeformed, neutral position (e.g., FIG. 8).Some frames comprise a super-elastic material (e.g., a shape-memorymaterial). Nitinol is an alloy comprising nickel and titanium (e.g.,between about 55% and about 57% nickel combined with a minimum of about42.85% titanium by weight, and traces (i.e., up to about 0.05% byweight) of carbon, oxygen and iron) that demonstrates super-elasticity(i.e., can elastically deform through strains as large as between about8% and about 10%).

The valve 100 shown in FIGS. 5A and 5B has an inlet end 102 and anoutlet end 104, a cloth-covered frame assembly 200 defining commissureposts 201 (also referred to herein as commissure portions) of the valveand three leaflets 300 coupled to the frame assembly. In the illustratedembodiment, the commissure posts 201 of the valve lean slightly outwardrelative to a central flow axis of the axis of the valve when the valveis in its neutral configuration. During diastole, the outlet end 104 cancontract such that the commissure posts lean inward of a neutralposition to define a diameter, D_(diastole) at the outlet end of thevalve that is slightly less than the diameter, D_(systole), at theoutlet end during systole, as shown in FIGS. 6A and 6B. As shown inFIGS. 7 and 33, the illustrated frame assembly 200 comprises acloth-covered stent and sewing ring sub-assembly 250 having asuture-permeable, annular sewing ring 260 extending circumferentiallyaround the inlet end 102 of the valve 100. A valve attachment portion,such as the illustrated annular sewing ring 260, can lie in asubstantially common plane 99′ with the inlet end 102 when the valve isin a neutral position, as shown in FIG. 7.

As discussed more fully below, the frame assembly 200 can be pliant andcan undergo substantial deformation from the neutral position shown inFIG. 5, allowing the frame 200 to be resiliently collapsed to a smallersize for delivery (e.g., the commissure tips 202 can move radiallyinward into a delivery position), and to self-expand from such acollapsed position (e.g., the commissure tips 202 can move radiallyoutward at least in part due to the resiliency of the frame). Since thevalve 100 is secured to a lumen by the stent and sewing ring subassembly250, the commissure tips 202 remain free to move relative to the sewingring. The leaflets 300 can open when exposed to a positive pressuregradient in a fluid (e.g., blood) passing between the inlet end 102 andthe outlet end 104 and close (or coapt) when exposed to a negativepressure gradient between the inlet end and the outlet end.

In other valves, the circumferentially extending sewing ring 260 (orother attachment portion) need not be located adjacent the inlet end 102and can be longitudinally spaced therefrom (e.g., the attachment portioncan be positioned between the inflow end and the outflow end). Disclosedattachment portions also need not lie entirely within a given plane 99′.In any event, and as more fully described below, disclosed valvescomprise an attachment portion having a sufficiently low profile(relative to the overall length of the valve) to allow respectivecommissure portions of the valve (e.g., the commissure tips 202) to moveindependently of the attachment portion.

Once a disclosed valve 100 is positioned at an implantation site, thecircumferentially extending attachment portion can engage and/or beattached to an inner periphery of the body lumen (e.g., a nativeannulus) at the implantation site. For example, disclosed prostheticvalves can be implanted in the aortic annulus, and the annular sewingring can be attached (e.g., sutured) to the fibrous annulus, or to theaorta wall, at a position downstream from the location of the naturalleaflets. Various forms of attaching the annular sewing ring to thefibrous annulus and/or aorta can be used, such as sutures, staples,adhesives and/or similar expedients.

Positioning the attachment portion relative to the valve body and theimplantation site, as just described, can allow portions of the frame(e.g., the cantilevered commissure portions 201 that extendlongitudinally of the sewing ring 260) to deflect independently of thesurrounding body lumen to which the valve is secured. Such independentdeflection provides several advantages. For example, cantileveredsupport structure of some disclosed valves can lean radially outward inan undeformed, neutral position, providing a larger outlet orifice forthe valve and a lower pressure gradient within a fluid passing throughthe valve. Nonetheless, outwardly leaning support structure can obstructaccess to a securing portion (e.g., sewing ring) when the valve is in aneutral position. In disclosed valves, such outwardly leaning (orneutral or inwardly leaning) cantilevered support structure can beretained radially inward of the valve securing portion duringimplantation, providing convenient access to the securing portion.

Body lumens, and in particular orifices of the heart, dilate andcontract with the cardiac cycle, as will now be described with referenceto FIGS. 6A and 6B. Some disclosed valves 100 can be so configured as toflexibly accommodate such radial contraction, as occurs during diastoleand dilation, as occurs during systole.

In some disclosed valves, the sewing ring 260 remains substantiallyundeformed during the cardiac cycle. In particular embodiments, thecommissure portions 201 of the valve are cantilevered and can flex withrespect to the sewing ring 260 and the prosthetic valve 100 and itslow-profile sewing ring 260 can be secured to the lumen within, orsubstantially adjacent to, a plane 99′. Typically, the pressure gradientacross the valve during systole is small enough (e.g., less than 10 mmHgin some embodiments) that the commissure portions remain in the neutralconfiguration and define a diameter at outlet end of the valve (referredto as systolic diameter D_(systole) in FIG. 6B). On the other hand,during diastole, the pressure gradient across the valve causes thecommissure portions to flex inwardly slightly so as to define a diameterat the outlet end of the valve (referred to as diastolic diameterD_(diastole) in FIG. 6A), smaller than the systolic diameter.Accordingly, the diameter measured between the commissure portions atthe outlet end 104 of the frame assembly can remain free to dilate andcontract during the cardiac cycle. The ability of the commissureportions to flex in this manner allows the leaflets supported by thecommissure portions to close more gently and relieves stress on theleaflets during diastole. In some implementations, the commissureportions can be configured to flex outward from the neutralconfiguration during systole (i.e., the commissure portions can flexfurther outward at the outlet end of the valve compared to theirconfiguration shown in FIG. 6B).

Moreover, because there is a lack of direct connection between theoutlet end 104 and the adjacent lumen (e.g., the aortic wall), the lumencan dilate naturally and without being constrained by the prostheticvalve 100 or its frame 200. For example, when a lumen dilates, points onan inner circumference of the lumen translate circumferentially withregard to each other (e.g., such points move farther apart from eachother as the lumen dilates). In contrast, valve outlets secured to aninterior of the lumen can resist (or constrain) the natural dilation ofthe lumen over a significant portion of the length of the valve. Byeliminating a direct connection between the outlet end 104 of theprosthetic valve 100 and the surrounding lumen, the lumen can remainsubstantially free to dilate naturally over a majority of the length ofthe valve. In some embodiments, the diastolic diameter of the valve(FIG. 6A) is smaller than the outer diameter at the outlet end of thevalve in a neutral configuration due, at least in part, to theresiliency and the flexibility of the commissure portions of the valveframe. Such dilation can relieve stress on the leaftlets during thecardiac cycle. In some embodiments, the systolic diameter is larger thanthe outer diameter at outlet end of the valve when the valve is in aneutral (e.g., an implanted neutral) configuration.

In operation, seams between adjacent leaflets 300 can separate under apositive pressure gradient through the valve (e.g., during systole) andcoapt under a negative pressure gradient through the valve (e.g., duringdiastole). In some disclosed valves, such separation and coaptation canbe improved by allowing radial movement of the commissure portions 201(e.g., corresponding to dilation and contraction of the body lumen)relative to the sewing ring 260.

Frame

As used herein, “wireform frame” (also sometimes referred to herein as a“wireform” or “wireform stent” means a three-dimensional body formed ofone or more wires or similarly shaped elongate members. In some frames,each of the one or more members has a substantially constantcross-sectional shape along its length. By way of example, such anelongate member can have a substantially solid, rectangular (e.g.,square) cross-sectional shape (e.g., as shown in FIG. 7). Othercross-sectional shapes (e.g., circular, annular, hollow rectangle) arealso possible. U.S. Pat. No. 6,558,418 describes a frame comprising morethan one elongate member that can be implemented in the valve 100, andis incorporated herein in its entirety. Also, the stent, or frame, ofthe valve need not be a “wireform” frame formed from wires. For example,the frame of the valve can be cut or otherwise formed from tubing or asheet of material and the individual components of the stent can havevarious cross-sectional shapes.

FIG. 7 shows a partial cross-sectional view through a cusp region 264 ofthe valve 100. As shown in FIG. 7, the frame assembly 200 can comprise acloth-covered wireform subassembly 220 (FIG. 5B) and a cloth-coveredstent and sewing ring sub-assembly 250 (FIG. 5B). The frame assembly 200can retain respective peripheral portions 302 of three leaflets 300between the cloth-covered wireform subassembly 220 and a cloth-coveredstent portion 270 (FIG. 33) of the stent and sewing ring sub-assembly250.

The illustrated cloth-covered wireform portion 220 comprises a wireformframe 230 (FIG. 8) and a wireform cover 245 (FIG. 30). As shown in FIG.7, the cover 245 surrounds the outer surface 231 of the wireform 230 andforms a seam 246 externally of the wireform in a region adjacent theperipheral portion 302 of the leaflet 300 on a side of the leafletpositioned opposite the stent and sewing ring sub-assembly 250.

The illustrated stent and sewing ring subassembly 250 comprises a stent270 (FIG. 36) and a sewing ring insert 280 (FIG. 39) joined and coveredby a rolled stent covering cloth 290 (FIG. 41). In an alternativeembodiment, the stent and sewing ring subassembly 250 can comprise astent 2600 (FIG. 45) and the sewing ring insert 280 (FIG. 39) joined andcovered by a rolled stent covering cloth 290 (see FIG. 41 and FIG. 46).The sewing ring portion 260 (e.g., the sewing ring insert 280 and theadjacent cloth 290) can be suture permeable (e.g., sutures can extendthrough the sewing ring) and can provide an attachment region forattaching the valve 100 to a surrounding region of a body lumen (notshown).

One embodiment of a wireform frame 230 is shown in FIG. 8. Theillustrated wireform 230 comprises a continuous elongate member havingan edulating shape around its periphery with a plurality of cuspportions 232 spaced from each other by respective, longitudinallyextending commissure portions 233. Each commissure portion 233 comprisesa pair of opposing commissure posts 234 extending from their proximalends adjacent respective cusps 232 to distal ends joined to each otherby a corresponding commissure tip 235. The illustrated commissure tipscomprise a single, narrow arcuate segment defining an upwardly convexarcuate tip. (Other commissure tips can comprise a pair of upwardlyconvex arcuate portions separated by an upwardly concave intermediateregion, giving such a commissure tip the appearance of “mouse ears,” asdisclosed in U.S. Pat. No. 7,473,275, which is incorporated herein inits entirety.) The proximal end of each commissure post 234 is joined toa respective cusp portion 232.

The wireform frame 230 shown in FIG. 8 has three cusp portions 232separated by three respective commissure portions 233. Other numbers ofcommissure portions (e.g., 2, 4, 5, etc.) are also possible. Theelongate member forming the wireform frame 230 shown in FIG. 8 has asubstantially square cross-sectional shape (FIG. 7).

As shown in FIGS. 5A, 5B, 8 and 12, each cantilevered commissure portion233 extends substantially vertically from (e.g., longitudinally of) thecusp portions 232 so as to define an inner, substantially cylindricalregion 236 of the frame. In other words, the tips 202 of the commissureportions are distally located relative to the cusp portions and anattachment portion (such as, for example, the sewing ring 260). That isto say, the commissure portions 233 are cantilevered such that the tips202 are free ends of the cantilevered structure. Such cantileveredcommissure portions 233 can allow the attachment portions of disclosedvalves to be secured at an implantation site while the valve is in acollapsed delivery position, as further described below. The inner,substantially cylindrical region 236 of the frame defines a longitudinalaxis 237 of the frame extending therethrough.

Each cusp portion 232 comprises a broad arcuate segment extendingbetween proximal ends of the commissure posts 234 adjacent therespective cusp portion. A plane 99 oriented substantially perpendicularto the longitudinal axis 237 of the frame 230 can be substantiallytangent to each of the cusp portions 232, as shown in FIG. 8. In someembodiments, a transverse cross section of the sewing ring 260 (FIG. 6)(a cross section substantially perpendicular to the longitudinal axis237) can lie entirely within a plane 99′ substantially parallel to theplane 99. In any event, the sewing ring 260 and the corresponding regionof attachment to the body lumen have sufficiently low-profiles as toallow the cantilevered commissure portions 233 to flex, as discussedabove.

Although the commissure portions 233 extend substantially vertically(axially) from the cusp portions 232 (e.g., are cantilevered), thecommissure portions can be oriented to lean inwardly or outwardly at aslight angle α relative to the longitudinal axis 237 (sometimes referredto as a “valve axis”). For example, when in a neutral configuration 238as shown in FIGS. 8 and 8A, the commissure portions 233 can extendradially outward of the cusp portions 232 (i.e., radially away from thelongitudinal axis 237) at an angle in the range of about 1 degree toabout 5 degrees, with 2 degrees being a specific example. In otherembodiments, the commissure portions 233 extend radially inward of thecusp portions 232 toward the longitudinal axis 237 of the frame, forexample, at an angle in the range of about 1 degree to about 5 degreeswhen in the neutral position 238.

Such inwardly and/or outwardly leaning, neutrally positioned commissureportions 233, when incorporated into an assembled prosthetic valve(e.g., the valve 100), can provide improved hemodynamics through thevalve. In other words, the extent to which the commissure portions 233lean inwardly or outwardly in the neutral position (and/or implantedneutral configuration) can be adjusted, together with the leaflet design(described below), to obtain desired pressure gradients through thevalve throughout the cardiac cycle when the valve is implanted.

As noted above, wireform frames can be formed from a super-elasticmaterial, such as, for example, Nitinol. Techniques for forming suchwireform frames are described more fully below with regard to FIGS.14-20. When formed of a super-elastic material, the wireform 230 can beelastically collapsed (e.g., longitudinally and/or radially) to asignificant degree (FIG. 9) without damaging the wireform (e.g., withoutplastically deforming or fracturing the wireform). Such a collapsedframe can self-expand and recover its original neutral configuration(e.g., FIG. 8). Other frame forming techniques are disclosed in U.S.Patent Publication 2004/0078950, which is hereby incorporated byreference in its entirety.

In FIG. 9, the wireform frame 230 shown in FIG. 8 is shown in a fullylongitudinally collapsed position 239 (e.g., for delivery) from whichthe frame can self-expand to the neutral configuration 238 shown in FIG.8. In the longitudinally collapsed position 239, the frame's commissuretips 235 (corresponding to the valve's commissure tips 202 shown inFIGS. 5A and 5B) are folded radially inward toward the longitudinal axis237 (FIG. 8) and relative to the cusp portions 232 until the tips 235reach respective collapsed positions 235′ (FIG. 9). Respective upwardfacing regions of the cusp portions 232 “roll” slightly inward towardthe longitudinal axis 237 to a longitudinally-collapsed cusp position232′ when the commissure tips are in their respective longitudinallycollapsed positions 235′. In this collapsed position 239, the interior236 of the frame 230 becomes a substantially conical shape 236′ ascompared to the substantially cylindrical shape defined by the frame inthe neutral position 238.

FIG. 10 shows a comparison of the neutral position 238 and the fullylongitudinally collapsed position 239 of the wireform frame 230 shown inFIG. 9. As discussed more fully below, a prosthetic valve 100 (FIGS. 5Aand 5B) in a longitudinally collapsed position 239, as shown in FIG. 9,allows convenient access to an inlet end 102 of the valve and/or asewing ring portion 260 for securing the valve 100 to a body lumenwithout interference by the commissure portions 233. In other words, byfolding the commissure portions inwardly as shown in FIG. 9, thecommissure portions (which may be outwardly leaning when the valve is ina neutral configuration, as shown in FIG. 8) do not interfere withaccess to the sewing ring portion 260, allowing the valve to be morequickly secured (e.g., sutured) to a surrounding tissue.

FIG. 11 shows a plan view from above the wireform frame 230 in a fullyradially-collapsed position 240 (e.g., for delivery) from which theframe can self-expand to the un-deformed, neutral configuration 238shown in FIG. 8 and FIG. 12. In the context of the wireform 230,radially collapsed means that base of at least one of the commissureportions 233 of the wireform 230 is displaced radially inwardly from theneutral configuration 238 shown in FIG. 12 toward the longitudinal axis237 and/or toward an opposing cusp 241 to a radially collapsed position233″ (so as to decrease a diameter and/or a spacing between thecommissure portion 233 and a diametrically opposing location on theframe 230), while the remaining commissure portions are leftsubstantially free to twist into a buckled configuration 242. Stateddifferently, the frame 230 can be placed to the radially collapsedconfiguration by pinching the frame at two diametrically opposedlocations adjacent the inflow end of the frame. In the radiallycollapsed configuration 240, the interior volume 236″ of the frame canbecome a substantially oval prism as shown, rather than a cylinder (orcircular prism), as in the neutral configuration.

FIG. 13 shows FIG. 11 and FIG. 12 superimposed on each other andillustrates the relative extent to which the radially collapsed position240 differs from the neutral position 238. As best seen in FIG. 13,cusps 243 positioned on opposing sides of the commissure portion 233 canbulge outwardly as compared to the same cusps 243 when the valve is inthe neutral position. Similarly, the cusp 241 can deflect inwardly to aflattened position. Such a radially collapsed position 238 can allow avalve 100 (FIGS. 5A and 5B) to more easily pass through an incision in aminimally invasive surgical technique, such as a thoracotomy and/or anaortotomy (e.g., by “shoe-horning” the valve through the incision, asdescribed more fully below).

With reference to FIGS. 14-27, several possible techniques for forming awireform frame 230 will now be described. As shown in FIG. 14, the frame230 can be formed starting with a sheet material 410. A laser cuttingprocess 415 can be applied to the sheet material 410 to form a laser cutflat pattern 420, as shown in FIG. 15. In alternative embodiments, thepattern for forming the frame can be formed from a sheet material 410 ortubing, using other suitable techniques, such as stamping, water-jetcutting, or chemical etching.

The exemplary flat pattern 420 shown in FIG. 15 comprises broadoutwardly convex portions 422 that comprise the cusps 232 of the frame230 shown in FIG. 8. Extending from opposing ends of the convex portions422 are lengths 424 of the pattern that comprise the commissure posts234 of the frame 230. As in the finished frame 230, distal ends ofopposing lengths 424 are joined by respective outwardly concave, arcuatesegments 426 that comprise the commissure tips 235 of the finished frame230.

As an alternative to forming a wireform frame 230 starting with a sheetmaterial, as just discussed, the frame can be formed starting with ahollow, cylindrical tube 430, as shown in FIG. 16. A laser-cuttingprocess 435 can be applied to the tube 430 to form a laser-cutcylindrical pattern 440 as shown in FIG. 17. The cylindrical pattern 440resembles the finished wireform frame 230 shown in FIG. 8. Thecylindrical pattern comprises cusps 442 extending between commissureportions 443. The commissure portions 443 comprise opposing commissureposts 444 extending from respective cusps 442 at their proximal end to adistal end joined to an adjacent distal end by an arcuate commissure tip445. At this stage, the cylindrical pattern 440 lacks any inward oroutward taper a (FIG. 8) of the commissure portions 443, and has not yetundergone a shape setting process to provide the Nitinol pattern 440with the shape memory of the finished wireform 230.

FIG. 18 shows a laser-cut pattern 420, 440 undergoing a first shapesetting process while being supported by a first mandrel 450. Thelaser-cut pattern 420, 440 can be installed on a body 452 of the firstmandrel such that cusp posts 453 engage respective cusp portions 422,442 of the pattern 420, 440. The mandrel body 452 can have a cylindricalor frusto-conical outer surface. For example, the body 452 of the firstmandrel can taper inwardly from a base adjacent the cusp posts 453 byabout 5°. A first annular mandrel cover 454 having an interior surfacecontour (e.g., tapering by about 5°) (not shown) corresponding to theexternal contour of the mandrel body 452 can urge against the commissureposts 424, 444 of the pattern. In other words, the annular mandrel cover454 defines an annular opening (not shown) between the cover and themandrel body 452. The cut pattern 420, 440 is positioned within thisannular opening.

Once positioned as just described, the pattern 420, 440, the mandrel andthe mandrel cover can be heated treated to shape set the pattern 420,440 to the desired shape. For example, the pattern 420, 440 can beheated to about 520 degrees Celsius (° C.) for about 8 minutes.

Afterward, the pattern 420, 440 can be placed on a second mandrel 460(e.g., having body 462 with an outward taper (relative to the firstmandrel body 452). In some instances, the outward taper of the secondmandrel 460 is about 2° relative to a longitudinal axis of the mandrel(not shown). A second mandrel cover 464 having an interior contour (notshown) corresponding to the external contour of the second mandrel body462 can be placed over the pattern 420, 440. The pattern can be heated,as described above. The two-step shape setting process described aboveis one example of a process that can be used to form the wireform 230.In other embodiments, shape setting can be accomplished in one step ormore than two steps.

Following heating on the second mandrel 460, the pattern can be removedand undergo a finishing process 470 (e.g., microblasting and/orelectropolishing). The completed wireform 480 shown in FIG. 20 has thefeatures described in connection with the wireform 230 shown in FIG. 8.

With reference to FIGS. 21-27, an alternative technique for forming thewireform 230 from a wire 500, such as, for example, a nitinol wire, willnow be described. Referring to FIG. 21, the wire 500 has opposing firstand second ends 502, 504 and a body 506 extending between the ends.

As shown in FIG. 22, the wire 500 can be installed on a firstwireforming mandrel 510 by wrapping the body 506 around pegs 511 a, 511b, 511 c and securing the first end 502 in a clamp, or jaws, 512.Shaping features 513 a, 513 b, 513 c can urge portions of the body 506extending between the pegs 511 a, 511 b, 511 c inwardly, as shown, toform concavely curved portions of the wire 500. The free second end 504can be pulled taught such that slack in the wire body 506 issufficiently removed. A second clamp, or jaws, 514 can tighten againstthe body 506 in a region adjacent the free second end 504.

Once the wire 500 has been positioned on the first wireforming mandrel510 as just described, the wire and the mandrel can be sufficiently heattreated such that the wire 500 substantially retains its on-mandrel formwhen removed from the mandrel 510, as shown in FIG. 23. For example,when removed from the mandrel 510, the wire 500 can define arcuatecommissure tips 521 a, 521 b, 521 c, 521 d formed by the respective pegs511 a, 511 b, 511 c, 511 a, and corresponding concave regions that formcusp portions 522 a, 522 b, 522 c of the finished frame 560 (FIG. 27),as well as the concave portion 522 d.

The shaped wire 520 is shown overlying a second wireforming mandrel 530in FIG. 24. The mandrel's body 531 defines pegs 532 and guides 533 b,533 c configured to hold the shaped wire 520 in position. For example,each of the commissure tips 521 a, 521 b, 521 c, 521 d can be positionedwith each tip extending around a corresponding peg 532, with the tips521 a and 521 d being positioned adjacent a single peg (not shown). Insuch a position, the opposing ends 502, 504 can extend downwardly of thesecond mandrel 530, as shown. The cusp portions 522 a, 522 b, 522 c andconcave portion 522 d can also be positioned adjacent correspondingmandrel guides (of which only the guides 533 b, 533 c are shown).

The shaped wire 520 and mandrel 530 can undergo a second heat treatingprocess (e.g., a shape setting process). Overlapping portions of theshaped wire 540 can be cut, as shown in FIG. 25, so as to defineopposing ends 502′, 504′ being positioned adjacent each other. A sleeve550 (also referred to as a “crimp sleeve”), as shown in FIG. 26,comprising a cylindrical body 551 having opposing open ends 552, 553 canbe used to join the opposing ends 502′, 504′, as shown in FIG. 27.

For example, in some instances, the body 551 defines an opening 554extending between the ends 552, 553. As shown in FIG. 27, the opposingends 502′, 504′ can be positioned within respective ends 552, 553 of thesleeve 550, and the body 551 can be sufficiently crimped adjacent theends 552′, 553′ such that the sleeve engages the shaped wire 540 ends502′, 504 of the wire at locations 552′, 553′ and forms a completedwireform frame 560 of the type shown in FIG. 8.

Leaflets

With reference to FIGS. 28 and 29, leaflets 300 as disclosed herein andbeing compatible with the disclosed valve 100 (FIGS. 5A and 5B), e.g.,allowing the commissure tips 235 to extend radially outward of thesewing ring 260, will be described by way of comparison to a leaflet 50of a conventional prosthetic valve (not shown). In alternativeembodiments, the valve 100 can include conventional leaflets 50, butthey can restrict movement of the commissure tips 235 and/or can besubject to undesirable stresses during the cardiac cycle.

The leaflet 300 shown in FIG. 29 comprises a leaflet body 301 andopposing, outwardly extending leaflet tabs 303 positioned on oppositesides of the leaflet body. The body 301 and tabs 303 collectively definean outlet periphery 304 (e.g., an edge) extending from an outermostcorner of one tab, across the one tab, the body and the other tab, to anoutermost corner of the other tab. The leaflet 300 also defines opposingregions 312 a, 312 b that can contact corresponding regions of anadjacent leaflet when the leaflets coapt under a negative pressuregradient, as described above. The opposing regions 312 a, 312 b arebounded by respective inlet boundaries 307 a, 307 b separating theregion of the leaflet body 301 that does not contact an adjacent leafletand the regions 312 a, 312 b that contact corresponding regions of anadjacent leaflet.

The outlet periphery 304 defines a first, lowermost region 310, opposingsecond, intermediate regions 308 a, 308 b, and opposing third, uppermostregions 313 a, 313 b. The opposing third regions 313 a, 313 b extend tothe respective regions 306 a, 306 b where the body periphery joins thecorresponding tabs 303. Each of the first, second and third regions hasa corresponding radius-of-curvature that, together, at least partiallydefine an outer contour of the body 301. The first region 310 and thethird regions 313 a, 313 b are separated by the second regions 308 a,308 b. The second regions 308 a, 308 b are separated from the respectiveadjacent third regions 313 a, 313 b at (or near) the point where theboundaries 307 a, 307 b intersect the outer periphery of the valve body301.

As shown in FIG. 28, the respective radii-of-curvature of the firstregion 310 (extending from about point B to about point C on the outerperiphery 304) and the third regions 313 a, 313 b (extending from aboutpoint A to corner 306 a of the adjacent tab 303 and from about point Dto corner 306 b of the adjacent tab 303) are greater than theradius-of-curvature of either of the second regions 308 a, 308 b(extending from about point A to about point B and from about point C toabout point D, respectively). The just-described body contour provides aleaflet body 301 that can allow an outlet end 104 of a valve 100 (FIGS.5A and 5B) to open more widely and/or to allow disclosed commissureportions of valves to extend radially outward to a larger degree thanconventional leaflets would allow, providing, at least in part, valveshaving the improved hemodynamics discussed above.

More specifically, the broad radius near the cusp and decreasing radiusof curvature approaching the commissure region introduces a small amountof slack in the leaflets. The leaflet design, in conjunction with theoutwardly leaning commissure posts 201, allow the leaflets to provide arelatively larger outlet opening for blood during systole, which reducesthe pressure gradient across the valve during systole.

Leaflets as disclosed herein can be formed using conventional materials,such as natural tissue (e.g., bovine, porcine, cadaver) or biocompatiblesynthetic materials.

Leaflet and Frame Assembly

As briefly discussed above in connection with FIGS. 5A and 5B, disclosedvalves 100 can comprise a cloth-covered frame assembly 200 and threeleaflets 300 coupled to the frame assembly. Assembly of a cloth-coveredframe assembly 220 will now be described with reference to FIGS. 30 and31.

FIG. 30 shows the frame 230 shown in FIG. 8 partially covered by a clothframe cover 245. Opposing ends of a strip of cloth 245 have been broughttogether to form a butt joint 247. Adjacent the butt joint 247, opposinglongitudinal edges 248, 249 of the cloth 245 have been wrapped around acusp portion 232 of the frame 230 and brought into opposing alignmentwith each other to form a seam 246 with the opposing edges. The seam 246can be completed by suturing, or other well known cloth-edge joiningtechniques. The cloth 245 can be wrapped around the entire elongateframe 230 as just described to arrive at the cloth-covered wire frameportion 220 shown in FIG. 31. Cloth covers can be formed of anybiocompatible fabric, such as, for example, polyethylene terephthalate.Other covering techniques are disclosed in U.S. Pat. No. 7,473,275,which is incorporated herein in its entirety.

Similar to the bare wireform frame 230, the cloth-covered wireform frame220 comprises cusp regions 222 separated by commissure portions 223.Each commissure portion comprises cloth-covered commissure posts 224extending from respective proximal ends adjacent respective cusps torespective distal ends joined to each other by an arcuate commissure tip225.

With reference to FIG. 32, a sub-assembly 350 comprising a cloth-coveredframe portion 220 and three leaflets 300 will be described. In thesub-assembly 350, three leaflets 300 as described above are positionedadjacent to each other in a tricuspid configuration. For example,opposing tabs 320, 321 of two leaflets 300 are positioned in opposingalignment. Stated differently, a portion of an interior surface 315(e.g., a region near the tab 321) opposes a corresponding interiorsurface (not shown) of the adjacent, opposing tab 320. As shown in FIG.33, the opposing pair of tabs 320, 321 is positioned between an opposingpair of commissure posts 224 such that the respective outlet edges ofthe leaflets are positioned adjacent the arcuate commissure tip 225 ofthe covered frame 220. Each of the other pairs of tabs 322, 323 and 324,325 is similarly positioned relative to each other and a respectivecommissure tip 225.

An outer peripheral portion of the body 301 of each leaflet 300 can besutured to the cloth cover 245 such that the cloth covered frame 220supports each leaflet in the tricuspid configuration, shown in FIGS. 26,27 and 28. For example, the portion adjacent the first region 310 of theperiphery can be attached to the cover 245 adjacent the cusp 232 of thecovered wireform frame 230 (FIG. 8). This configuration of leafletsprovides a closed, fluid occluding surface when exposed to negativepressure gradients (e.g., during systole), and separates to form anopen, unobstructed aperture when exposed to positive pressure gradients(e.g., during diastole), as shown in FIGS. 6A and 6B.

Lower Stent/Frame

Referring to FIG. 36, a lower stent, or frame, 270 as disclosed hereinis shown in a neutral position 270A and will be described. Theillustrated stent 270 defines an interior, substantially cylindricalvolume 271 defining a longitudinal axis 272 of the stent. The stentcomprises a circumferentially extending base member 273. As shown, somebase members can define longitudinally displaced undulations 274relative to, and positioned between, adjacent cusps 275. Each of aplurality of posts 276 extends longitudinally from a proximal end 277adjacent a respective undulation 274 to a distal end 278 defining a posttip 279. In some instances, such a stent can be formed from any flexiblebiocompatible polymer, such as, for example, polypropylene. In anotherimplementation, the stent 270 can be made of silicon with or without acloth core.

The primary functions of the stent 270 are to provide additional supportstructure for supporting the leaflets in the triscuspid configurationunder working conditions and to provide a structure to which the sewingring can be attached. The stent is also sufficiently flexible to allowthe valve to be longitudinally and/or radially collapsed to a smallerconfiguration for delivery.

Similar to the wireform 230, the stent 270 can undergo high levels ofstrain without suffering plastic deformation or other damage. Forexample, FIGS. 37 and 38 illustrate isometric and side elevation views,respectively, of the stent 270 in a longitudinally collapsed position270B. In the illustrated position, each of the post tips 278 have beenfolded radially inward from their respective neutral positions 270A(FIG. 36) and toward the longitudinal axis 272 of the stent. Similar tothe wireform frame 230 in its longitudinally collapsed position 239(FIG. 9), the longitudinally collapsed position 270B of the stent 270forms a substantially conically shaped interior volume 271′, as shown inFIGS. 37 and 38. Although not illustrated, the stent 270 can be radiallycollapsed in a manner similar to the wireform frame 230, as shown inFIGS. 11 and 13.

FIGS. 45-47 illustrate another embodiment of a collapsible stent 2600that can be used in place of stent 270. FIG. 45 shows a leaflet supportstent 2600 that includes a stent frame 2602 and a plurality ofcommissure tips 2604. The stent frame 2602 can be, for example, aflexible (e.g., radially compressible) stent frame comprising, forexample, Nitinol or other superelastic material. The commissure tips2604 can comprise, for example, a biocompatible polymer such as apolyester.

The stent frame 2602 can be shaped to include three cusp supportportions 2614 and three commissure portions 2608 spaced apart from oneanother, with a commissure portion 2608 positioned between each pair ofadjacent cusp portions 2614. A commissure tip 2604 can be secured toeach of the commissure portions 2608 of the stent frame 2602. Forexample, the commissure tips 2604 can each include one or more sewingholes 2606 through which sutures 2610 can be passed and then wrappedaround the respective commissure portion 2608, thereby securing eachcommissure tip to each respective commissure portion 2608. Othersuitable means of attachment can also be used.

The leaflet support stent 2600 can have a reduced thickness as comparedto other collapsible stents. For example, some embodiments of theleaflet support stent 2600 can be configured to have at least about a 1mm lower profile than the stent 270 described above. In someembodiments, while the stent 270 may have a thickness of around 1.5 mm,some embodiments of a leaflet support stent 2600 can allow for a reducedthickness of around 0.5 mm. For example, the leaflet support stent 2600can be formed from a wire having a thickness of around 0.5 mm. When thevalve portion of a prosthetic heart valve is positioned on top of theleaflet support stent 2600, the overall height of the prosthetic valvecan therefore be reduced by around 1 mm as compared to the height of theoverall prosthetic valve that includes the stent 270.

While the commissure tips 2604 are shown positioned on the inside of thestent frame 2602, they can alternatively be positioned on the outside ofthe stent frame 2602. In alternative embodiments, similar commissuretips can be configured to be positioned on top of the commissureportions 2608, and thus neither inside nor outside the stent frame 2602.In some embodiments, the commissure tips can be formed integrally withthe stent frame. The commissure tips 2604 can be secured to the stentframe 2602 such that the commissure tips 2604 are substantiallyprevented from moving in the axial direction with respect to the stentframe 2602. However, the coupling of the commissure tips 2604 to thecommissure portions 2608 can be configured so as not to interfere withthe radial collapsibility of the overall leaflet support stent 2600.

The leaflet support stent 2600 can be combined with a sealing ring(e.g., sealing ring 280 shown in FIG. 39) and covered in cloth 290 asdescribed above to form a collapsible stent subassembly 2700, seen inFIG. 46. As shown in FIG. 46, the cloth-covered stent frame 2602′, thecloth-covered commissure tips 2604′, and the cloth-covered sealing ring280 form the collapsible stent subassembly 2700.

FIG. 47 shows the subassembly 2700 in a radially collapsedconfiguration. Some embodiments of the subassembly 2700 can be radiallycompressed to a relatively smaller diameter than the collapsible stentof FIGS. 36-38, as shown, and return to its expanded, unstressedconfiguration shown in FIG. 46 when any external crimping restraint isremoved. When the subassembly 2700 is radially compressed, thecloth-covered commissure posts 2604′ can remain substantially vertical(e.g., substantially parallel to the axial direction of the leafletsupport stent) such that they do not interfere with the radialcompressibility of the subassembly 2700. Additional details concerningembodiments of a collapsible leaflet support stent 2600 are disclosed inU.S. Patent Application No. 61/472,083, which is incorporated herein byreference.

Sewing Ring Insert

With reference to FIGS. 39 and 40, an example of a sewing ring insert280 will now be described. The body 281 of the illustrated sewing ringinsert 280 comprises a frustoconical, annular body-of-rotation. In otherwords, the illustrated body 281 defines a body of rotation about asewing ring axis 282 extending longitudinally of the body. The body 281defines a major circumference 283 having a major diameter D and a minorcircumference 284 having a minor diameter d, and a tapering wall 285extending between the major circumference and the minor circumference.The wall 285 can have a relatively smooth (i.e., untextured) innersurface 286. The wall can have an outer surface 287 that is roughened,or provided with retention features (e.g., ridges, including barbs 288,as shown in FIGS. 39 and 40).

As described more fully below in context of the prosthetic valveassembly 100, the illustrated ridges formed by the outer surface 287 canprovide the sewing ring portion 260 with an uneven outer contour thatcan engage the surrounding tissue of the implantation site. Suchengagement can provide the prosthetic valve with improved purchase atthe implantation site (e.g., as compared to only suturing the valve).

For example, the taper of the wall 285 can facilitate placement at adesired implantation site as the minor diameter first comes into contactwith the surrounding tissue of the lumen. As the sewing ring is urgedlongitudinally into the lumen, the tissue can expand and slidelongitudinally of the outer surface 287. The barbs or other retentionfeatures 288 can engage the surrounding tissue and at least partiallyretain the sewing ring within the surrounding lumen until the sewingring can be permanently secured in place, as by suturing.

In addition, such ridges can stiffen the sewing ring insert 280, addingto the resiliency of the sewing ring portion 260. Even so, the sewingring 260 preferably is flexible for allowing the valve 100 to collapse(e.g., radially collapse). In some embodiments, the sewing ring insert280 comprises a silicone-based material, although other suture-permeablematerials can be used. Other sewing ring inserts 280 can comprise arelatively stiff, or even a rigid, material. In such embodiments, theextent to which the valve can be radially collapsed may be limited, butthe cantilevered commissure portions can still be folded inwardly tolongitudinally collapse the valve for delivery.

Stent and Sewing Ring Sub-Assembly

Assembly of the stent and sewing ring sub-assembly will now be describedin connection with FIGS. 7 and 34.

Referring to FIG. 41, a tubular (e.g., cylindrically tubular) stentcovering cloth 290 is shown axially aligned with the stent 270 and thesewing ring insert 280. In other words, the longitudinal axis of thecovering cloth 290 is co-axially aligned with the respectivelongitudinal axes 272, 282 of the stent 270 and the sewing ring 280. Thecovering cloth 290 can comprise any suitable biocompatible fabric.

The whole of the stent 270 can be inserted into the interior of thetubular cloth 290. The sewing ring insert 280 can also be inserted intothe interior of the tubular cloth 290. As best shown in FIG. 7, thesewing ring insert and the stent can be co-centrically positioned withrespect to each other such that the insert 280 circumscribes the base273 and the minor circumference 284 of the insert is aligned with thelower edge of the base 273 of the stent 270.

The tubular cloth has a length L extending between its respective openends 291 and measuring more than about twice the length l of the stent270 (measured from a cusp portion 275 to a post tip 278 (FIG. 36). Oncethe stent 270 and the sewing ring insert 280 have been positioned withinthe tubular cloth 290, a free end portion 292 of the cloth can be foldedinwardly on itself. In other words, a “top” edge 293 corresponding tothe free end portion 292 can be rolled inwardly toward the tube'sinterior and pulled through the cylindrical interior 271 of the stent270 (FIG. 36), so as to line both the interior and exterior surfaces ofthe stent with the cloth 290 and to juxtapose the opposing ends 291 ofthe tubular cloth.

Referring to the cross-section shown in FIG. 7, the juxtaposed ends 291can overlap, as shown by the overlapping cloth 294 adjacent the barbs ofthe sewing ring insert 280. Excess cloth adjacent the cusps 273 and/orposts can be rolled to form the roll 292. In some instances, such seamsare sutured.

In other embodiments, a leaflet support stent 2600 (FIG. 45) can be usedin place of stent 270 as described above, with the sewing ring insert280 and cloth covering 290 coupled to the leaflet support stent 2600instead of collapsible stent 270.

Final Assembly of a Prosthetic Valve

As shown in FIG. 5B, the stent and sewing ring subassembly 250 as justdescribed and illustrated can be coupled to the subassembly comprisingthe wireform portion 220 and corresponding leaflets 300, to assemble thevalve 100.

As shown in the exploded view of FIG. 5B, the subassembly 250 canmatingly engage a corresponding contour of the covered wireform 220. Inother words, as shown, for example, in FIG. 5B, the covered posts 256 ofthe assembly 250 can be so sized and shaped as to overlie, or beinserted within, corresponding commissure portions 353 of the wireform230 and leaflet assembly 350. Once in position, the cloth covering ofthe posts 256 and stent can be sutured to the cloth covering of thewireform 220, so as to substantially complete the prosthetic valveassembly 100. In addition, if desired, covers 295 can be positioned overthe exposed portions of the commissure tabs of the leaflets, and securedin place with sutures 296 (FIG. 5B). The covers can be formed of anysuitable biocompatible fabric.

Delivery Systems

Examples of delivery systems for disclosed prosthetic valves will now bedescribed. Valves as described herein can be delivered to theimplantation site manually, or with the assistance of amanually-controlled instrument 600 (FIGS. 42A-42D) and/or one or moresutures 450 (FIG. 43).

In some embodiments, access to the sewing ring 260 can be at leastpartially obstructed by one or more portions of the valve 100 (e.g.,longitudinally extending commissure portions 201). For such embodiments,it may be convenient to longitudinally collapse the valve 100 to, and toretain the valve in, a longitudinally collapsed delivery position (e.g.,the frame 230 is shown in such a configuration in FIG. 9). By way ofexample, a suture can couple the commissure tips 202 (FIG. 5A) to eachother, or to another portion of the valve, such as a cusp portion of theframe, so as to maintain the collapsed position 239 (FIG. 9) and toprevent the frame from self-expanding to the neutral position 238.

A longitudinally collapsed valve can, in some embodiments, also beradially collapsed (e.g., FIG. 11) to aid insertion of the collapsedvalve through a relatively small incision (e.g., using a “shoe-horning”technique, as described more fully below). One or more sutures can beused to retain the valve in a radially collapsed position.

In some delivery systems, a single suture can be used to retain thevalve in the longitudinally and the radially collapsed positions justdescribed. In such a system, cutting the suture allows the valve toself-expand to its original neutral position (and/or to an implantedneutral configuration). In other delivery systems, one or more suturesused to retain the valve in the longitudinally collapsed position areindependent of the one or more sutures used to retain the valve in theradially collapsed configuration. In this approach, the valve 100 canremain longitudinally collapsed upon releasing the valve from theradially collapsed position. This can be useful, for example, duringimplantation, since the radially collapsed valve can be more easilyinserted through an incision in the lumen, and a radially expanded valvecan be more easily secured in the lumen, particularly when the valveremains longitudinally collapsed such that the cantilevered commissureportions do not interfere with access to the securing portion of thevalve (e.g., the sewing ring). Once the longitudinally collapsed valvehas been adequately secured within the lumen, the valve can be releasedfrom its longitudinally collapsed position and allowed to self-expand tothe implanted neutral configuration.

As noted above, a manually-controlled instrument, or delivery device 600(FIGS. 42A-42D), can be used to assist delivery of disclosed valves toan implantation site. For example, as shown in FIG. 42D, the illustratedinstrument 600 comprises a handle 610 and optional actuators (not shown)at a proximal end of the instrument and a valve holder 630 at a distalend of the instrument.

The holder 630 can be configured to secure a valve 100 to the instrumentand/or to retain the valve in a collapsed deployment configuration(e.g., a radially collapsed configuration and/or a longitudinallycollapsed configuration). In other words, a valve retained in itscollapsed configuration (e.g., by sutures) can be held by the holder630. In particular embodiments, the instrument is configured toselectively retain and release a valve from a radially and/orlongitudinally collapsed configuration by actuation of various actuatorson the handle 610.

A shaft 620, which can be flexible and/or deformable, extends betweenthe handle 610 and the holder 630. The holder 630 in the illustratedembodiment comprises a central hub 634 and a plurality of angularlyspaced leg portions 632 a, 632 b, 632 c extending from the hub 634. Theleg portions 632 a, 632 b, 632 c are positioned relative to thecommissure posts 201 of the valve 100 such that each leg portion isaligned behind and bear against a respective commissure post so as toretain the commissure post in a longitudinally collapsed position (asbest shown in FIG. 42B). In contrast, the most common way of deliveringa surgical valve involves securing the leg portions of a valve holderbetween two adjacent commissure posts of the valve. In any case, as bestshown in FIG. 42A, the leg portions 632 a, 632 b, 632 c can bereleasably secured to the commissure posts, such as with a suture orwire 636 that is threaded through apertures in the holder and throughthe sewing ring 260 at the base of each commissure post. The legportions retain the commissure posts in the longitudinally collapsedposition during delivery and suturing of the valve to a native annulusand can be released from the longitudinally collapsed position bymanually cutting and removing the suture 636 or actuating an actuator onthe handle 610 that automatically causes the leg portions to release thecommissure posts.

As shown in FIG. 42C, the valve can also be retained in a radiallycollapsed configuration, such as by employing another suture or wire 638that is threaded through opposing locations on the sewing ring 260 andpulled taught to cause the sewing ring to collapse radially. In thisradially collapsed position, the valve appears to be pinched on oppositesides of the sewing ring. The suture 638 can be tied off to a convenientlocation on one of the leg portions of the valve holder as shown. Thevalve can be released from the radially collapsed configuration afterdelivery to the implantation site by manually cutting and removing thesuture 638 or actuating an actuator (e.g., a lever or trigger) on thehandle 610 that automatically releases tension on suture 638, which inturn allows the sewing ring to self-expand back to its functional size.Such an actuator can be configured to apply and release tension onsuture 638 so as to collapse and expand the valve, respectively, asneeded by the operator.

In certain embodiments, the shaft 620 can be hollow so as to convey oneor more linkages coupling the actuators and the holder. Such linkagescan activate the holder 630 (e.g., retain the valve in a collapsedposition, release the valve from a collapsed position and/or pivot theholder relative to the shaft) by actuation of various actuators on thehandle. Some delivery instruments 600 comprise an articulatable joint(not shown) between the holder 630 and the shaft 620. Such a joint, whenactivated, can assist the operator in performing a shoehorning insertiontechnique.

As noted above, the collapsed valve can be introduced to a body lumenusing the “shoehorning” technique. Referring to FIG. 43 for example, anunder-sized incision 13 (relative to a cross-sectional dimension of thevalve 100 in its neutral position) can be made in the lumen wall (e.g.,the descending aorta). The collapsed valve (e.g., radially and/orlongitudinally collapsed) can be inserted through the incision at anangle relative to a plane defined by the incision, much like passing abutton through a button-hole. After insertion through the incision, thevalve can be released from its radially collapsed position, and thesewing ring 260 can be secured to the implantation site 11. As notedabove, the commissure portions of the valve are desirably retained in alongitudinally collapsed configuration during suturing for increasedaccess to the sewing ring. After being secured, the valve can bereleased from its longitudinally collapsed configuration and allowed toself-expand to the implanted neutral configuration.

As mentioned above, a disclosed valve 100 can be implanted in a bodylumen with the assistance of the delivery instrument 600. To implant avalve using the instrument 600, a surgeon can open an outer incision(e.g., in the patient's thorax), and a second, incision in the lumen inwhich the valve is to be implanted (e.g., an aortotomy 13 (FIG. 43)).The valve 100 can be mounted to the holder 630 and placed in a radiallyand longitudinally collapsed state as depicted in FIG. 42C. The holderand collapsed valve can be inserted through the outer incision, and theshaft 620 can extend to the opened lumen, placing the collapsed valveadjacent the second incision. With some delivery devices, actuators inthe handle can be actuated to articulate the holder 630 to avoid anatomyas the holder 630 passes through the patient's thorax, and/or throughthe lumen incision. After the valve is passed through the incision inthe lumen, the valve can be released from the radially collapsedposition, such as by cutting or releasing tension in suture 638, andthen positioned against the native annulus (e.g., the aortic annulus12). The valve can then be secured in place by suturing the sewing ring260 to the native annulus, after which the valve can be released fromthe longitudinally collapsed state, such as by cutting suture 636 torelease the holder 630 from the valve. Retracting the holder 630 awayfrom the valve allows the commissure posts 201 to self-expand to animplanted neutral configuration.

As shown in FIG. 43, and to assist in the delivery of a collapsed valveto the implantation site (e.g., the aortic annulus), an array of implantsutures 450 can be secured around the periphery 11 of the native annulus12, and the opposite ends of the sutures can be pulled through theincision 13 and threaded through the sewing ring 260 of the prostheticvalve 100. The prosthetic valve can be “parachuted” down the array ofsutures until the valve rests against the native annulus, and thesutures 450 can be tied off to secure the prosthetic valve to theannulus. This “parachuting approach” can be used independently of, or incombination with, the delivery instrument 600. In any case, after thevalve is passed through the incision 13 and before it is secured to theannulus 12, the valve can be released from a radially collapsed state asdescribed above. Once the valve is sutured to the annulus 12, the valve100 can be released from the longitudinally collapsed state (and/or fromthe delivery apparatus 600), the delivery apparatus is removed from thebody and the incisions in the lumen and thorax can be closed.

In alternative embodiments, the valve 100 can be implanted within theheart using any known techniques. For example, the valve 100 can bedelivered and implanted using a conventional valve holder that does notretain the valve in a collapsed delivery configuration (either aradially or longitudinally collapsed configuration).

EXAMPLE

Multiple valves 100 were constructed in nominal sizes of 19 mm, 23 mm,and 25 mm. The valves 100 were placed in a testing apparatus andsubjected to a 20 lpm steady-state flow. FIG. 44 shows the pressuregradient measured across the valves 100 (identified as “Valve B” in FIG.44) and the pressure gradient measured across various sizes of a knownvalve (identified as “Valve A”) at a 20 lpm steady-state flow and a 5lpm pulsatile flow. The valve A configuration had a conventional leafletconfiguration (leaflet 50 in FIG. 28) and a rigid frame havingcommissure posts extending substantially perpendicularly to the sewingring. As can be seen in FIG. 44, valve B experienced a lower pressuredrop than valve A at all three sizes of valve B.

Other Embodiments

Many embodiments of prosthetic valves and delivery systems beingcompatible with minimally invasive surgical techniques are possible byincorporating one or more of the principles described above. Thisdisclosure makes reference to the accompanying drawings which form apart hereof, wherein like numerals designate like parts throughout. Thedrawings illustrate features of specific embodiments, but otherembodiments may be formed and structural changes may be made withoutdeparting from the intended scope of this disclosure.

Directions and references (e.g., up, down, top, bottom, left, right,rearward, forward, etc.) may be used to facilitate discussion of thedrawings but are not intended to be limiting. For example, certain termshave been used such as “up”, “down”, “upper”, “lower”, “horizontal”,“vertical”, “left”, “right”, and the like. Such terms are used, whereapplicable, to provide some clarity of description when dealing withrelative relationships, particularly with respect to the illustratedembodiments. Such terms are not, however, intended to imply absoluterelationships, positions, and/or orientations. For example, with respectto an object, an “upper” surface can become a “lower” surface simply byturning the object over. Nevertheless, it is still the same surface andthe object remains the same. As used herein, “and/or” means “and”, aswell as “and” and “or.”

Accordingly, this detailed description shall not be construed in alimiting sense, and following a review of this disclosure, those ofordinary skill in the art will appreciate the wide variety of prostheticvalves that can be devised and constructed using the various conceptsdescribed herein. Moreover, those of ordinary skill in the art willappreciate that the exemplary embodiments disclosed herein can beadapted to various configurations without departing from the disclosedconcepts. Thus, in view of the many possible embodiments to which thedisclosed principles can be applied, it should be recognized that theabove-described embodiments are only examples and should not be taken aslimiting in scope. Therefore, we claim all that comes within the scopeand spirit of the following claims.

We claim:
 1. A prosthetic valve comprising: a plurality of valveleaflets; a collapsible, self-expandable frame assembly configured tosupport the valve leaflets and defining a plurality of commissureportions, wherein the self-expandable frame assembly comprises anundulating continuous elongated wireform member alternately definingconvex cusp portions on an inflow end thereof intermediate convexcommissure portions on an outflow end thereof, made from a super elasticalloy such that each of the commissure portions is configured to befolded radially inward to a longitudinally collapsed position fordelivery of the valve to an implantation site within a body lumen; and asewing ring comprising an annular suture-permeable member for contactinga surrounding lumen, the sewing ring being attached to the valve at theinflow end and radially outward of the frame assembly cusp portions,wherein the plurality of commissure portions are adapted to becantilevered and not in contact with the surrounding lumen andconfigured to move independently of the sewing ring when it is incontact with the surrounding lumen.
 2. The prosthetic valve of claim 1,wherein each of the commissure portions is cantilevered relative to thesewing ring such that a commissure tip can move relative to the sewingring.
 3. The prosthetic valve of claim 1, wherein at least one of thecommissure portions is configured to be collapsible to a radiallycollapsed position for delivery of the valve.
 4. The prosthetic valve ofclaim 1, wherein each of the plurality of commissure portions extendsradially outward of the cusp portions when the frame assembly is in aneutral configuration.
 5. The prosthetic valve of claim 1, wherein eachof the leaflets is so configured as to allow the plurality of commissureportions of the frame assembly to flex radially outwardly and inwardlyrelative to the sewing ring during the cardiac cycle.
 6. The prostheticvalve of claim 5, wherein each of the plurality of leaflets defines acorresponding outer periphery with first, second and third regions,wherein each of the first, second and third regions has a correspondingradius-of-curvature, wherein the first and third regions are separatedby the second region, and wherein the respective radii-of-curvature ofthe first and third regions is greater than the radius of curvature ofthe second region.
 7. The prosthetic valve of claim 1, wherein theself-expandable frame assembly comprises: a first subassembly comprisingthe continuous elongated wireform member; and a second subassemblycomprising the sewing ring, wherein at least a portion of each of theleaflets is supported between corresponding portions of the firstsubassembly and the second subassembly.
 8. The prosthetic valve of claim1, wherein the wireform member comprises nitinol.
 9. The prostheticvalve of claim 1, wherein the self-expandable frame assembly comprises:a first subassembly comprising the continuous elongated wireform memberthat defines the commissure portions; and a second subassemblycomprising the sewing ring and a stent coupled together with fabric,wherein the stent comprises a circumferential base member and aplurality of posts that extend longitudinally therefrom adjacent theplurality of commissure portions, and wherein each stent post may befolded radially inward so as to be longitudinally collapsible along witha corresponding commissure portion.
 10. The prosthetic valve of claim 9,wherein the stent is formed of a single polymer piece.
 11. Theprosthetic valve of claim 9, wherein the stent is formed of silicon. 12.The prosthetic valve of claim 9, wherein the circumferential base memberof the stent is separate from a plurality of commissure tips that formthe posts.
 13. The prosthetic valve of claim 12, wherein the commissuretips are secured to the circumferential base member with sutures. 14.The prosthetic valve of claim 12, wherein the commissure tips are formedof a polymer while the circumferential base member is formed of a superelastic alloy.
 15. A prosthetic valve comprising: a plurality of valveleaflets arranged to provide one-way longitudinal flow through the valveeach having an outlet edge opposite an arcuate peripheral edge; acollapsible, self-expandable frame configured to support the valveleaflets and defining a plurality of convex commissure portionscantilevered in an outflow direction, wherein the self-expandable framecomprises a superelastic alloy such that the frame may be collapsed fordelivery of the valve, wherein the frame comprises an undulatingcontinuous elongated wireform defining a plurality of convex cuspportions intermediate the commissure portions; and a stent subassemblyconfigured to secure the valve to a surrounding lumen, the stentsubassembly comprising a stent having a circumferential base member withcusps that coincide with and align longitudinally with respective onesof the frame cusp portions and a plurality of posts that extendlongitudinally therefrom adjacent and to an outside of respective onesof the plurality of commissure portions of the frame, the stentsubassembly being attached to the self-expandable frame with the arcuateperipheral edges of the valve leaflets being secured between the alignedframe cusp portions and the stent cusps, while the outlet edges attachat their ends to the frame commissure portions and adjacent stent posts,and wherein the stent subassembly may be collapsed in the same manner asthe frame for delivery of the valve, and wherein the valve is expandabletoward a neutral configuration and collapsible to a collapsed deliveryconfiguration for delivery of the valve to an implantation site within abody lumen.
 16. The prosthetic valve of claim 15, wherein at least oneof the commissure portions is configured to be collapsible to a radiallycollapsed position for delivery of the valve.
 17. The prosthetic valveof claim 15, wherein each of the plurality of commissure portionsextends radially outward of the cusp portions when the frame is in aneutral configuration.
 18. The prosthetic valve of claim 15, whereineach of the plurality of leaflets defines a corresponding outerperiphery defining first, second and third regions, wherein each of thefirst, second and third regions has a corresponding radius-of-curvature,wherein the first and third regions are separated by the second region,and wherein the respective radii-of-curvature of the first and thirdregions is greater than the radius of curvature of the second region.19. The prosthetic valve of claim 15, wherein the frame comprisesNitinol.
 20. The prosthetic valve of claim 15, wherein each commissureportion of the frame and each stent post of the stent may be foldedradially inward to convert the valve to the collapsed deliveryconfiguration.
 21. The prosthetic valve of claim 15, wherein the stentis formed of a single polymer piece.
 22. The prosthetic valve of claim15, wherein the stent is formed of silicon.
 23. The prosthetic valve ofclaim 15, wherein the circumferential base member of the stent isseparate from a plurality of commissure tips that form the posts. 24.The prosthetic valve of claim 23, wherein the commissure tips aresecured to the circumferential base member with sutures.
 25. Theprosthetic valve of claim 23, wherein the commissure tips are formed ofa polymer while the circumferential base member is formed of a superelastic alloy.
 26. The prosthetic valve of claim 15, wherein the frameis covered with a cloth cover having opposing longitudinal edges broughtinto opposing alignment with each other to form a seam, and the stentsubassembly is also covered in cloth, wherein the arcuate peripheraledges of the valve leaflets are secured between the aligned frame cuspportions and the stent cusps by sutures that pass through the seam ofthe frame cloth cover, through the leaflets, and through the clothcovering the stent subassembly.
 27. The prosthetic valve of claim 26,further including a sewing ring attached around an outside of the stentsubassembly and attached to the cloth covering thereon.
 28. Theprosthetic valve of claim 15, further including a sewing ring attachedaround an outside of the stent subassembly for contacting a surroundinglumen.